Paramagnetic Resonance of Mn⁺⁺ Associated with Impurities in Alkali Chlorides

Abstract

The paramagnetic resonance absorption of Mn⁺⁺ ions associated with the impurities of fluorine or divalent anions has been investigated in the single crystals of NaCl and LiCl. A resolved fine structure was observed in a “not quenched crystal” and it did not fade into a broad single line in contrast with the spectra of Mn⁺⁺ ions which had been usually observed in alkali halides. The ground level splitting parameters have been determined in the spin Hamiltonian DS₁²+E(S₂²−S₃²) as follows: D=(−420±1)·10⁻⁴ cm⁻¹, |E|=(65±1)·10⁻⁴ cm⁻¹ for Mn⁺⁺−F⁻, D=(−511±5)·10⁻⁴ cm⁻¹, |E|=(25±5)·10⁻⁴ cm⁻¹ for Mn⁺⁺−X⁻⁻, a manganese divalent anion pair, in NaCl, and D=(−672±5)·10⁻⁴ cm⁻¹, |E|=(12±3)·10⁻⁴ cm⁻¹ for Mn⁺⁺−X⁻⁻ in LiCl, the principal axes of the spin Hamiltonian being in nearly agreement with the cubic axes of the crystal. The large value of D suggests the existence of the strong attractive force between Mn⁺⁺ and impurity ion.